LibreOffice using AI against Microslop/anything related to it doesn't feel very Libreoffice of it to me.

I know that this pattern is used by AI but it only said this is, one time not two times and then continued with It is rather than the pattern that you mention. An AI would've probably used "This" second time instead of "It" most likely given that its probably really trained on it.

I mean, we do use "this is" in a sentence atleast once like they did.

How else do you want them to write this point :/

I don't think that Libreoffice team is using AI to write their messages.